FOR MORE THAN A CENTURY, most U.S. courts have recognized a balanced definition of legal insanity. Last week, the Supreme Court rejected it.
In an opinion by Justice David H. Souter, who is usually more sensitive to defendants' rights, the court spurned the appeal of Eric Clark, who was 17 when he shot a Flagstaff, Ariz., policeman after the officer stopped his pickup truck. The teenager was convicted for "intentionally or knowingly" killing a law enforcement officer even though Clark, who had a history of delusional behavior, said he thought the cop was a space alien.
Souter, writing for himself and five colleagues (Justice Stephen G. Breyer opted out of some parts of the majority opinion) in the 6-3 ruling, said the Constitution's guarantee of due process did not prevent Arizona from lopping off one of two prongs of a definition of legal insanity known as the M'Naghten rule.
That rule, which originated in England in 1843, allows for an insanity plea when a defendant, because of a mental disease, either does not know the "nature and quality" of his actions or doesn't realize that those actions are wrong. Arizona deleted the reference to the "nature and quality" of the act, meaning that it was sufficient for the state to prove that Clark knew he had done wrong by introducing evidence that he fled from the scene.
Despite the long pedigree of the M'Naghten rule in both Britain and the United States, Souter said that "the insanity rule, like the conceptualization of criminal offenses, is substantially open to state choice."
The immediate effect of the ruling will be limited because only a handful of states have gone as far as Arizona in weakening M'Naghten. (California's penal code preserves both prongs of the rule, though it has eliminated an additional defense known as "diminished capacity.") Still, the decision sends a signal to legislators in other states that M'Naghten is fair game.
The irony is that until the 1980s, the M'Naghten rule was viewed as the stricter definition of legal insanity. Prosecutors preferred it to a more liberal formula used by some courts allowing a defendant to mount an insanity defense if he "lacked substantial capacity to conform his conduct to the requirements of the law." Although presidential assailant John W. Hinckley Jr. was acquitted under this liberal test, public outrage over the verdict moved some states to make it harder to cite insanity as a reason for acquittal. In Arizona, what Clark was denied was not an acquittal by reason of insanity but a verdict of "guilty except insane," which would have permitted him to be sent to a mental institution rather than prison -- the same fate as Hinckley.
Clark's killing of Officer Jeffrey Moritz was a horrific tragedy that might have been averted if Clark had been institutionalized. But once the deed was done, the courts -- including the high court -- should have given him more of an opportunity to prove that bad acts are sometimes committed by mad people.